Recent advances in optomechanical technology, such as the development of micromodulators, have been applied to projection display systems.
A projection display comprised of micromodulators has been described by Younse in IEEE Spectrum at 27-31 (November 1993). In Younse's display, micromirrors are suspended over address electrodes and memory cells of a CMOS static ram. Each micromirror is associated with a particular memory cell. The micromirrors are suspended at diagonally opposed corners, which allows them to tilt under the action of bias. Bias is provided by a data signal which is stored on the address electrode. Electrostatic forces between the address electrodes and the mirror tilt the associated mirror either +10 degrees or -10 degrees. Light reflected from a mirror having a +10 degree tilt is imaged by a projection lens onto a screen. Light reflected from a mirror having a -10 degree tilt will not be imaged by the projection lens. Shading from white to black is determined based on the time during each video frame that the mirror is imaging through the projection lens. An image is created on the screen by the action of many such micromirrors.
The modulator described by Younse is only suitable for projection displays, since it works by deflecting light through specific angles. It may not be used for direct-view displays. For certain applications, such as very small displays, a projection-based display is unsuitable.